Numerous types of stickers and graphics are available in the market today that are of the self-adhesive type or may be applied after coating with an adhesive. There are also numerous adhesives available for securing an image that is pre-applied onto a special water release paper, and then transferred to a painted or unpainted surface. However, removal of the sticker material along with the image is a cumbersome process and usually results in damage to the underlying surface.
There is a need in the market place for a strong composite structure that can be used as a temporary removable graphic, which can be easily applied, and when desired, can be easily removed without damage to the underlying substrate. Potential uses for such a temporary removable graphic are as an advertisement, logo, label, banner, sign, instructions, color coding, identification and many other functional situations that identify, protect or decorate substrates. A composite structure is needed that can be applied to concrete, brick, asphalt, tar, parking lots, terrazzo, parquet, wood, glass, metals, plastics, ceramics, elastomers, rubber, fabrics, textiles and other painted or unpainted substrates.
There is also a complete absence in the market for a suitable system and method that may be used as an indoor or outdoor temporary removable floor graphic. This is difficult to accomplish today, because items such as graphics or signs are not durable enough and cannot be used on walking and driving surfaces as they do not have the necessary strength and resistance properties to fulfill the service life required. Also, they cannot be easily removed from substrates without damage to the underlying surface.
Graphics or signs are applied to substrates by standard techniques such as screen printing, gravure printing, flexographic printing or hand-painting, to form finished products. The graphics cannot be easily removed from the substrates, especially painted or coated substrates without damage to the underlying surfaces. Aggressive solvents such as toluene, xylene, methylethyl ketone, ethyl acetate, acetone, trichloroethylene, hexane and other hydrocarbon mixtures of solvents would usually be required to remove the adhesive and printing ink, and would result in damage to painted substrates and many other substrates such as plastics.
Graphics and signs can also be applied to substrates using a paper, film and an adhesive. The film or coated paper has graphics printed on the surface or on the reverse side of the film or coated paper. Also, on the reverse side of the surface an adhesive is applied in the form of a pressure sensitive adhesive or a remoistenable adhesive followed by some type of release paper in certain situations. The graphic or sign is applied by peeling away the release paper and applying to various substrates. An example of this would be a label stuck on a wooden object or a label put on an automobile body. In both cases, the label cannot be easily removed from the substrate without possible surface damage.
There is a need for a composite structure that can be applied to an outdoor surface such as a floor, a wall, a painted vehicle body, a marine or aeronautical craft body, to serve as an advertisement or sign for an extended period of time. Wind, rain, sunlight or other environmental factors should not adversely affect the performance of the composite structure. At a designated time, the advertisement or sign can be easily removed without damage to the underlying substrates. After removal and clean up, a new advertisement or sign can be repeatedly re-applied to the same surface.
A practical application would be to apply an advertisement to outdoor vertical and horizontal surfaces by applying graphics on concrete, asphalt, brick or cement block and to an indoor floor such as a painted or unpainted concrete or terrazzo floor in a shopping mall or store. The advertisement or sign should have a composite structure that would be easy to apply, easy to remove but would have sufficient properties to be used on an outdoor or indoor walking and driving surface such as a parking lot or a floor in a shopping mall.
Another practical application would be to apply an advertisement, sign or graphic to the body of an auto vehicle, marine or aeronautical craft, that would have sufficient properties to last for an extended period of time outdoors including repeated automatic or manual washing using a detergent or windshield washing with an ammonia solution. When desired, the advertisement, sign or graphic could be easily removed without damage to the surface. If required, a fresh temporary removable graphic could be re-applied onto the same surface.
Traditionally, the transfers of images are of two types: those which have a dry release; and those which have a wet release. The wet release graphics have an image printed on a paper which is pre-coated with a layer of water soluble gum. The back side of the printed image is usually coated with a water remoistenable glue. When the graphic is soaked with water and pressed on a surface on which the image is to appear, the soluble gum layer partially dissolves and becomes soft, so that the paper may be removed, leaving the image on the desired surface. The paper on which the image is printed is known as a wet release paper. This is normally made up of an absorbent paper of good quality which is coated with some type of water soluble starch or vegetable gum to act as a release layer. The paper or backing serves as a support for the release layer and subsequent layers of ink and adhesive.
The image may be applied on the paper with standard methods, such as printing, copying or drawing directly or in reverse, depending on the final surface. A wide variety of inks are used, and the image can be applied by standard methods such as silk screening, offset printing, digital printing or toner based laser printout.
Normally, the process begins by application of a coat of lacquer or varnish on the gum coated side of the paper surface. Then the image is printed on the lacquer, and a water remoistenable glue is coated on to the dried surface of the ink. To apply the graphics, it is submerged in water for a short while, causing the water soluble gum layer to release the paper from the image. The image and adhesive composite structure is slid off from the paper, and transferred to the substrate for its intended long-term use.
The graphics need to be protected on the outer face by a polymeric top coating as a key part of the composite structure. The polymeric coating must be flexible, clear, durable, have good resistance properties to ultraviolet light, water, humidity, rain, snow, heat, cold, pollution, common cleaning chemicals and soaps. The polymeric coating must be able to be applied from solution or in a molten state by various application methods to yield consistent, quality films. Inks, decorative and functional coatings must be able to be applied to the dried polymeric film. Back coatings must be able to be applied to the composite polymeric coating and ink structure. The polymeric coating must have the unique ability to have the necessary service life properties and be able to be removed easily with a remover without leaving any residue or damaging the substrate.